The invention relates to a dryer and more particularly to a dryer for the chemical industry which functions to allow both fresh air operation and return air operation.
One prior art dryer is disclosed in European Pat. No. 60,212. The prior art dryer has a very complicated structure and is difficult to use. In the prior art arrangement, a fan basket in the ceiling part of the housing extends directly into the drying chamber and draws off the flow of gas from the chamber. On the exhaust side, the fan basket in the ceiling part directs the flow of gas as a main flow along the back wall of the drying chamber, where a heating device is located, and down past the division plate to the back side of a loading car that is located in the drying chamber. The main flow of gas then passes through the loading car in the longitudinal direction. The ceiling part of the chamber on the exhaust side has a control device which directs a secondary flow along the side walls and into the drying chamber where condensers are located. The secondary flow is suctioned back by a fan on the suction side of the chamber. Since the secondary flow of gas is led directly to the condensers, heat is lost through the fan rather than being absorbed by the material to be dried.